In recent years, the degree of attention for a minute mechanical system (also called MEMS (Micro Electro Mechanical System) and a micro-machine) produced by a microscopic processing technology developed with a semiconductor and the like has been increasing. Among these micro-machines, there is technology in which a silicon substrate and a borosilicate glass substrate (hereafter, referred to as a glass substrate) containing movable ions are made in contact with each other, and on this condition, a silicon wafer and a glass substrate are bonded by an anode bonding.
As an example utilizing an anode bonding technology, there is an ink jet head disclosed by Patent Document 1. This ink jet head is configured in a three layer structure in which a nozzle plate (upper substrate) at an upper side and an electrode substrate (lower substrate) at a lower side are laminated across a cavity plate (intermediate substrate). The intermediate substrate is made of a silicon substrate, and the upper substrate and the lower substrate are made of a glass substrate. The lower substrate and the intermediate substrate are brought in contact with each other and are held in this contact condition. The upper substrate is held on a non-contact condition above them, and the lower substrate and the intermediate substrate are heated to increase their temperature, and then, the lower substrate and the intermediate substrate are bonded by an anode bonding. Thereafter, the upper substrate is shifted downward onto the surface of the intermediate substrate, and the upper substrate and the intermediate substrate are bonded by the anode bonding.
Further, in Patent Document 2, there is an example in which plural silicon substrates are arranged on both sides of a glass substrate, and the silicon substrates and the glass substrate are bonded by an anode bonding. In this case, the glass substrate is made a little bit larger than the silicon substrate, and the bonding is conducted on the condition that a cathode is brought in contact with a part of the glass substrate located at the outside of the overlapped portion between the glass substrate and the silicon substrate.    Patent document 1: Japanese Unexamined Patent Publication No. 11-192712 official report    Patent document 2: Japanese Unexamined Patent Publication No. 11-87201 official report